/*
-----------------------------------------------------------------------------
This source file is part of OGRE
(Object-oriented Graphics Rendering Engine)
For the latest info, see http://www.ogre3d.org/

Copyright (c) 2000-2006 Torus Knot Software Ltd
Also see acknowledgements in Readme.html

This program is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the Free Software
Foundation; either version 2 of the License, or (at your option) any later
version.

This program is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details.

You should have received a copy of the GNU Lesser General Public License along with
this program; if not, write to the Free Software Foundation, Inc., 59 Temple
Place - Suite 330, Boston, MA 02111-1307, USA, or go to
http://www.gnu.org/copyleft/lesser.txt.

You may alternatively use this source under the terms of a specific version of
the OGRE Unrestricted License provided you have obtained such a license from
Torus Knot Software Ltd.
-----------------------------------------------------------------------------
*/


#ifndef COMPILER2PASS_H
#define COMPILER2PASS_H

#include <vector>

#ifdef _WIN32
#define WIN32_LEAN_AND_MEAN
#define NOMINMAX // required to stop windows.h messing up std::min
#include <windows.h>
#endif

// FIX ME - should not be hard coded
#define BAD_TOKEN 999

typedef unsigned int uint;



/** Compiler2Pass is a generic compiler/assembler
@remarks
	provides a tokenizer in pass 1 and relies on the subclass to provide the virtual method for pass 2

	PASS 1 - tokenize source: this is a simple brute force lexical scanner/analyzer that also parses
			 the formed token for proper semantics and context in one pass
			 it uses Look Ahead Left-Right (LALR) ruling based on Backus - Naur From notation for semantic
			 checking and also performs	context checking allowing for language dialects

	PASS 2 - generate application specific instructions ie native instructions

@par
	this class must be subclassed with the subclass providing implementation for Pass 2.  The subclass
	is responsible for setting up the token libraries along with defining the language syntax.

*/
class Compiler2Pass {

protected:

	// BNF operation types
	enum OperationType {otRULE, otAND, otOR, otOPTIONAL, otREPEAT, otEND};

	/** structure used to build rule paths

	*/
	struct TokenRule {
		OperationType mOperation;
		uint mTokenID;
		const char* mSymbol;
		uint mErrorID;

	};

	/** structure used to build Symbol Type library */
	struct SymbolDef {
	  uint mID;					// Token ID which is the index into the Token Type library
	  uint mPass2Data;			// data used by pass 2 to build native instructions

	  uint mContextKey;			// context key to fit the Active Context
	  uint mContextPatternSet;	// new pattern to set for Active Context bits
	  uint mContextPatternClear;// Contexts bits to clear Active Context bits

	  int mDefTextID;			// index into text table for default name : set at runtime
	  uint mRuleID;				// index into Rule database for non-terminal toke rulepath
								// if RuleID is zero the token is terminal

	};


	/** structure for Token instructions */
	struct TokenInst {
	  uint mNTTRuleID;			// Non-Terminal Token Rule ID that generated Token
	  uint mID;					// Token ID
	  int mLine;				// line number in source code where Token was found
	  int mPos;					// Character position in source where Token was found

	};

	typedef std::vector<TokenInst> TokenInstContainer;
	//typedef TokenInstContainer::iterator TokenInstIterator;

	/// container for Tokens extracted from source
	TokenInstContainer mTokenInstructions;

	/// pointer to the source to be compiled
	const char* mSource;
	int mEndOfSource;

	/// pointers to Text and Token Type libraries setup by subclass
	SymbolDef* mSymbolTypeLib;

	/// pointer to root rule path - has to be set by subclass constructor
	TokenRule* mRootRulePath;

	/// number of entries in Text and Token Type libraries
	int mRulePathLibCnt;
	int mSymbolTypeLibCnt;

	/// mVauleID needs to be initialized by the subclass before compiling occurs
	/// it defines the token ID used in the symbol type library
	uint mValueID;


	/// storage container for constants defined in source
	std::vector<float> mConstants;

	/// Active Contexts pattern used in pass 1 to determine which tokens are valid for a certain context
	uint mActiveContexts;

	/** check token semantics between ID1 and ID2 using left/right semantic data in Token Type library
	@param ID1 token ID on the left
	@param ID2 token ID on the right
	@return
		true if both will bind to each other
		false if either fails the semantic bind test

	*/
	//bool checkTokenSemantics(uint ID1, uint ID2);

	/** perform pass 1 of compile process
		scans source for symbols that can be tokenized and then
		performs general semantic and context verification on each symbol before it is tokenized.
		A tokenized instruction list is built to be used by Pass 2.

	*/
	bool doPass1();

	/** pure virtual method that must be set up by subclass to perform Pass 2 of compile process
	@remark
		Pass 2 is for the subclass to take the token instructions generated in Pass 1 and
		build the application specific instructions along with verifying
		symantic and context rules that could not be checked in Pass 1

	*/
	virtual bool doPass2() = 0;

	void findEOL();

	/** get the text symbol for this token
	@remark
		mainly used for debugging and in test routines
	@param sid is the token ID
	@return a pointer to the string text
	*/
	const char* getTypeDefText(const uint sid);

	/** check to see if the text at the present position in the source is a numerical constant
	@param fvalue is a reference that will receive the float value that is in the source
	@param charsize reference to receive number of characters that make of the value in the source
	@return
		true if characters form a valid float representation
		false if a number value could not be extracted
	*/
	bool isFloatValue(float & fvalue, int & charsize);

	/** check to see if the text is in the symbol text library
	@param symbol points to begining of text where a symbol token might exist
	@param symbolsize reference that will receive the size value of the symbol found
	@return
		true if a matching token could be found in the token type library
		false if could not be tokenized
	*/
	bool isSymbol(const char* symbol, int & symbolsize);


	/// position to the next possible valid sysmbol
	bool positionToNextSymbol();


	/** process input source text using rulepath to determine allowed tokens
	@remarks
		the method is reentrant and recursive
		if a non-terminal token is encountered in the current rule path then the method is
		called using the new rule path referenced by the non-terminal token
		Tokens can have the following operation states which effects the flow path of the rule
			RULE: defines a rule path for the non-terminal token
			AND: the token is required for the rule to pass
			OR: if the previous tokens failed then try these ones
			OPTIONAL: the token is optional and does not cause the rule to fail if the token is not found
			REPEAT: the token is required but there can be more than one in a sequence
			END: end of the rule path - the method returns the succuss of the rule

	@param rulepathIDX index into to array of Token Rules that define a rule path to be processed
	@return
		true if rule passed - all required tokens found
		false if one or more tokens required to complete the rule were not found
	*/
	bool processRulePath( uint rulepathIDX);


	// setup ActiveContexts - should be called by subclass to setup initial language contexts
	void setActiveContexts(const uint contexts){ mActiveContexts = contexts; }


	/// comment specifiers are hard coded
	void skipComments();

	/// find end of line marker and move past it
	void skipEOL();

	/// skip all the white space which includes spaces and tabs
	void skipWhiteSpace();


	/** check if current position in source has the symbol text equivalent to the TokenID
	@param rulepathIDX index into rule path database of token to validate
	@param activeRuleID index of non-terminal rule that generated the token
	@return
		true if token was found
		false if token symbol text does not match the source text
		if token is non-terminal then processRulePath is called
	*/
	bool ValidateToken(const uint rulepathIDX, const uint activeRuleID);


public:
	// ** these probably should not be public
	int mCurrentLine;
	int mCharPos;


	/// constructor
	Compiler2Pass();
    virtual ~Compiler2Pass() {}
	/** compile the source - performs 2 passes
		first pass is to tokinize, check semantics and context
		second pass is performed by subclass and converts tokens to application specific instructions
	@remark
		Pass 2 only gets executed if Pass 1 has no errors
	@param source a pointer to the source text to be compiled
	@return
		true if Pass 1 and Pass 2 are successfull
		false if any errors occur in Pass 1 or Pass 2
	*/
	bool compile(const char* source);

	/** Initialize the type library with matching symbol text found in symbol text library
		find a default text for all Symbol Types in library

		scan through all the rules and initialize TypeLib with index to text and index to rules for non-terminal tokens

		must be called by subclass after libraries and rule database setup
	*/

	void InitSymbolTypeLib();

};

#endif

